Accurate volumetric quantification of atherosclerotic disease is critical in a number of clinical situations. We propose to develop and validate three-dimensional intravascular ultrasound methodology to quantify changes in volumetric distribution of atherosclerotic disease. In the Phase-I of this project new image processing algorithms will be developed to more accurately detect complex lumen borders. Realistic experiments will be designed to test the fundamental assumption that the displacement of the imaging device inside the artery is well represented by the displacement measured outside the body. Phantoms with known shapes will be constructed and volumetric analysis will be performed to determine accuracy and reproducibility. In the Phase-II of this project, we will enhance the software features with database support, angiographic visualization and tissue characterization. Rigorous in-vivo studies will also be performed to develop the methodology as a validated clinical tool. The product will not only have clinical application in evaluating interventional procedures, but will also be an effective tool for monitoring regression and restenosis. PROPOSED COMMERCIAL APPLICATION: The product will provide a validated tool for accurate in-vivo quantification of volumetric changes in atheroma distribution. The Primary market will be clinical sites that perform intravascular ultrasound imaging. There is an installed based of 1200 intravascular ultrasound units worldwide and with the advent of stents the market is projected to grow at a rate of 250 units per year. Secondary markets will include research applications for which the rate of atherosclerotic progression or regression must be quantified.